In general, halitosis is caused by acquired systemic disease or substances inducing malodor, produced through degradative action of certain enzymes such as decarboxylase, or deaminase (L-cysteine desulfhydrase or L-methionine--lyase) on amino acids resulting from the decomposition of salivary proteins, food particles, and the like by microorganisms in the oral cavity. Sulfide compounds, which are contained in ingested garlic or hot pepper, are also responsible for oral malodor. Main components causing halitosis comprise volatile sulfide compounds (hereinafter referred to as “VSC”) including, for example, hydrogen sulfide (H2S), methyl mercaptan (CH3SH), dimethyl mercaptan ((CH3)2S) and the like. Particularly, methylmercaptan is known as a main compound of offensive odor contributing to halitosis. Volatile amine compounds including trimethyl amine ((CH3)3N) or δ-aminovaleric acid causing fishy stink resulting from staleness of fishes are also major compounds responsible for oral malodor. Other substances causing oral malodor include aldehydes, fatty acids, ammonia and pyridines.
In addition, methods of eliminating halitosis by removing such VSC are disclosed in prior patents including Korean Pat. Laid-open Publication No. 97-8154 and Japanese Pat. Laid-open Publication No. 60-75418.